Varstrometry for Off-nucleus and Dual sub-Kpc AGN (VODKA): Dubious Dual Quasars as Gravitationally Lensed Systems

In today’s Universe of hierarchical galaxy formation, galactic mergers are thought to be an important mechanism for galaxy evolution while also fueling central black hole accretion. In some instances, two galactic nuclei in the merging galaxies can be triggered simultaneously, leading to a dual Active Galactic Nucleus (dAGN) system. We probe this scenario using a sample of suspected dual quasars at Cosmic Noon (z~2), the period of highest merger and AGN activity. Selected based on the astrometric jitter (varstrometry) observed in Gaia images, I will focus on one particularly intriguing candidate that shows seemingly conflicting evidence of being either a dual quasar or a single object lensed by a foreground galaxy. We find that the optical, IR, and UV photometric and spectroscopic evidence points to a lensing scenario, while the radio and X-ray imaging and spectra show distinctly different patterns that suggest a dAGN. I will discuss these results alongside other candidates from our VODKA sample, highlighting the need for a panoply of wavebands and techniques when hunting dual AGN systems. Constraining the occurrence of these merging systems is a top priority for the broader community since they are expected to lead to black hole coalescence and emission of gravitational waves that could potentially be detected by future missions like LISA.